Saturday, 28 November 2015

Life Percolating at Depth

First, there was the microbe that scientists found living in lightless solitude more than two miles down a South African gold mine. Nothing alive had ever been found at that depth before.

Then there was the “Worm From Hell,” the first complex, multicellular creature found living at almost equal depths in the same group of mines.

Now the researchers who made both of those discoveries have hit another jackpot: the discovery of a “veritable zoo” of multi-cellular creatures living in the wet rock fissures of the gold and diamond mines of the Witwaterstrand Basin of South Africa, roughly a mile below the surface.

The creature found in 2011 – Halicephalobus mephisto – is a tiny nematode and are the deepest-living terrestrial multi-cellular organisms on earth. It’s an animal that lives where no other animals were thought to exist, in the rocky underworld known as the “deep subsurface”.

To H.mephisto, the subterranean world is an all-you-can-eat buffet. They feed on bacteria and other microbes that grow in rich mats on the rocky surface. There’s no risk of starving underground.

The earlier discoveries had already dramatically changed scientists’ understanding of life in the underworld.

The number and variety of creatures found so deep has proven that previous estimates of the amount of life (biomass) underground and under the bottom of the oceans have been too low. Those estimates have ranged from 20 percent to 50 percent of the total mass of life on Earth.

The rod-shaped D. audaxviator was recovered from thousands of litres of water collected deep in the Mponeng Mine in South Africa in 2008.